This invention relates generally to tactile imaging paper which is capable of producing a raised pattern when written upon with a writing fluid, and more particularly concerns a tactile imaging paper comprising a backing sheet laminated with polyethylene film to a tactile sheet that has been densified by dry calendering to enhance the height of the raised image on the paper.
In the past, various schemes have been proposed for facilitating nonverbal communications with the visually impaired. The most common method of nonverbal communication with the visually impaired is Braille which is a widely used tactile method of communication. Braille is a six position code of dots of two columns and three rows. Depending on the location and combination of the dots, letters, numbers, words, or phrases are denoted. Braille communication, however, is limited to alpha numeric communication and does not provide any means for depicting pictorial representations such as graphs, maps, or other representations that are not alpha numeric. Another common scheme for nonverbal communications for the visually impaired is the Sewell drawing kit. This device consists of a board with a hard rubber surface and clips that hold a piece of cellophane over the surface. A sharp instrument, carefully manipulated, is used to scratch the cellophane surface thereby raising a welt which can be felt and deciphered by the visually impaired. The Sewell drawing kit requires both a fine touch in drawing the image on the cellophane and a very delicate touch to decipher the raised welts.
A number of other prior art methods of nonverbal communication for the visually impaired are set forth in U.S. patent application Ser. No. 160,803, filed Feb. 26, 1988, by Traylor et al. The Traylor et al. reference discloses a writing paper suitable for communication with a visually impaired person which writing paper comprises a cellulosic sheet on which the application of a writing fluid causes an expansion of the cellulosic material to produce a raised pattern readable by touch. The pattern remains readable after the writing fluid has dried. The cellulosic sheet is formed from a 75:25 blend of Aquasorb F-C (superabsorbent carboxymethylated cotton and/or other linters) and hardwood pulp. The writing fluid contains a hardening agent, for example, a monosaccharide such as sucrose or a polysaccharide such as starch, so that upon drying, the raised pattern remains hard and readable to the touch. The cellulosic sheet is laminated to a polyester film to increase the height of the raised pattern, to preserve the integrity of the sheet, and to inhibit strikethrough of the writing fluid. The high percentage of superabsorbent fibers in the tactile imaging paper of the Traylor et al. reference is commercially unattractive because the superabsorbent fiber is substantially more expensive than conventional wood pulps used in paper making.